Flexible packaging can be an attractive option for the storage and dispensing of flowable materials, especially where the materials are to be isolated from the outside environment. Such materials can include, for example, curable or otherwise hardenable adhesives, coatings, sealants, and fillers used for vehicle body repair. One widely used type of flexible packaging is a collapsible container. Typically, this collapsible container is inserted into a reusable housing, and a cap with an outlet port is mounted to an opened end of the container for directing the materials toward an intended target. During use, external pressure is applied to the container, which collapses as its contents are dispensed through the outlet port. When depleted, the container can be simply disposed of, resulting in minimal cleanup.
It is generally desirable to form a seal between the opened end of the package and the cap to efficiently convey the materials through the outlet port and prevent leakage. This can be technically challenging, since the cap and housing are often rigid while the walls of the collapsible container are comparatively soft and pliable. Different approaches have been implemented. In one approach, a small amount of a glue or other hardenable composition is applied between the inner perimeter of the cap and the collapsible container. This glue often serves not only a structural purpose in connecting the package to the cap but also a barrier purpose in preventing the materials from seeping through the seam between these two components. Another approach is to configure the interior geometry of the cap such that a hermetic seal is formed between the cap and collapsible container when positive pressure is applied between the package and the cap.